A media sensor is a device to determine different media types. A media sensor is typically used in a printing module so that the printing module may adjust the printing methods according to the media type of the print medium.
FIG. 1 depicts a schematic diagram of a conventional media sensing system 10. The conventional media sensing system 10 includes a conventional media sensor 12 and a print medium 14. The print medium 14 represents any type of media such as different types of printing paper. The conventional media sensor 12 includes an optical emitter 16 and two optical detectors 18 and 20. The optical emitter 16 generates light directed toward a surface of the print medium 14. The light is then reflected by the print medium 14 into specular and diffuse components. In FIG. 1, the specular reflection component is indicated by the solid arrows. Similarly, the diffuse reflection component is indicated by the dashed arrows, although the diffuse reflection component is reflected in a variety of directions.
As the print medium 14 is fed in (e.g., in the direction of the arrow), the optical detectors 18 and 20 detect the specular and diffuse reflectance components. In particular, the optical detector 20 is approximately at the specular reflection angle relative to the optical emitter 16 to detect the specular reflection component. The other optical detector 18 detects the diffuse reflection component of the reflected light. By converting the detected specular and diffuse reflection components to quantifiable values, the media type of the print medium is determined by comparing the values with known values for typical print media.
However, the resolution of the optical detector 16, or the ability of the optical detector 16 to differentiate among a variety of media types, is low because output ranges (i.e., diffuse and specular reflectance values) of different media overlaps significantly.